Adult Deformity Correction Research Articles

P52. Pelvic incidence changes with adult deformity correction: is intraoperative measurement needed?

P52. Pelvic incidence changes with adult deformity correction: is intraoperative measurement needed?

P163. Radiographic and clinical outcome analysis of custom vs surgeon contoured rods for adult deformity correction at 12 months postoperative

P163. Radiographic and clinical outcome analysis of custom vs surgeon contoured rods for adult deformity correction at 12 months postoperative

The Association of Lumbar Plexus Lengthening With Neurological Deficit After Adult Spinal Deformity Surgery.

Retrospective cohort study. This study aimed to evaluate the association between nerve lengthening after adult deformity correction and motor deficits dervied from the upper lumbar plexus or femoral nerve. Adult spinal deformity (ASD) surgery is associated with high rates of neurological deficits. Certain postoperative deficits may be related to lengthening of the upper lumbar plexus (ULP) and/or femoral nerve (FN) after correction of lumbar deformity. Patients with ASD who underwent posterior-only corrective surgery from the sacrum to L3 or above were included. The length of each lumbar nerve root was calculated geometrically using the distance from the foramen to the midpoint between the anterosuperior iliac crest and pubic symphysis on AP and lateral radiographs. The mean lengths of the L1 to 3 and L2 to 4 nerve roots were used to define the lengths of the ULP and FN, respectively. Preoperative to postoperative changes in nerve length were calculated. Neurological examination was performed at discharge. Proximal weakness (PW) was defined as the presence of weakness compared with baseline in either hip flexors or knee extensors. Multiple linear regression analysis was used for estimating the postoperative lengthening according to the magnitude of preoperative curvature and postoperative correction angles. A total of 202 sides were analyzed in 101 patients, and PW was present on 15 (7.4%) sides in 10 patients. Excluding the 10 cases with three-column osteotomies, those with PW had a significantly higher rate of pure sagittal deformity ( P <.001) and greater nerve lengthening than those without PW (ULP 24 vs. 15mm, P =0.02; FN 18 vs. 11mm, P =0.05). No patient had advanced imaging showing neural compression, and complete recovery of PW occurred in eight patients at one-year follow-up. After ASD surgery, lengthening of the ULP was associated with PW. In preoperative planning, surgeons must consider how the type of correction may influence the risk for nerve lengthening, which may contribute to postoperative neurological deficit.

Single-position Minimally Invasive Surgery for Correction of Adult Spinal Deformity.

Minimally invasive adult spinal deformity (MIS ASD) surgery may offer benefits over conventional techniques in select circumstances. The success of the procedure is based on proper patient selection, restoring adequate alignment, and optimizing fusion. In the past, MIS techniques were limited because of the need to reposition the patient-a source of increased surgical time and potentially patient risk. New developments now allow for single-position, MIS correction of adult deformity. Additional research will be needed to determine the ideal patient for minimally invasive adult spinal deformity surgery and whether prone or lateral single-position confers the best outcomes.

How Much Lumbar Lordosis does a Patient Need to Reach their Age-Adjusted Alignment Target? A Formulated Approach Predicting Successful Surgical Outcomes.

Retrospective cohort study. Identify optimal lumbar lordosis in adult deformity correction to achieve age-adjusted targets and sustained alignment. Surgical adult spinal deformity patients reaching an age-adjusted ideal alignment at one year were identified. Multilinear regression analysis was used to identify the relationship between regional curvatures (LL and TK) that enabled achievement of a given global alignment (T1 pelvic angle, TPA) based on pelvic incidence (PI). 347 patients out of 1048 available reached their age-adjusted TPA within 5° (60-year-old, 72% women, body mass index 29 ± 6.2). They had a significant improvement in all sagittal parameters (except PI) from pre-operative baseline to 1year following surgery (P < .001). Multilinear regression predicting L1-S1 based on TK, TPA, and PI demonstrated excellent results (R2 = .85). Simplification of the coefficients of prediction combined with a conversion to an age-based formula led to the following: LL = PI - 0.3TK - 0.5Age + 10. Internal validation of the formula led to a mean error of -.4°, and an absolute error of 5.0°. Internal validation on patients with an age-adjusted alignment revealed similar accuracy across the entire age-adjusted TPA spectrum (ranges of LL errors: ME = .2° to 1.7°, AE = 4.0° to 5.3°). This study provides a simple guideline to identify the amount of LL needed to reach a given alignment (i.e., age-adjusted target) based on PI and associated TK. Implementation of this predictive formula during pre-operative surgical planning may help to reduce unexpected sub-optimal post-operative alignment outcomes.

Perioperative Predictive Factors for Positive Outcomes in Spine Fusion for Adult Deformity Correction.

Purpose: Identifying perioperative factors that may influence the outcomes of long spine fusion for the treatment of adult deformity is key for tailored surgical planning and targeted informed consent. The aim of this study was to analyze the association between demographic or perioperative factors and clinical outcomes 2 years after long spine fusion for the treatment of adult deformity. Methods: This study is a multivariate analysis of retrospectively collected data. All patients who underwent long fusion of the lumbar spine for adult spinal deformity (January 2016–June 2019) were included. The outcomes of interest were the Oswestry disability index (ODI), visual analogic scale (VAS) preoperatively and at 1 and 2 years’ follow up, age, body mass index, American Society of Anaesthesiologists (ASA) score, upper and lowest instrumented vertebrae (UIV and LIV, respectively), length of surgery, estimated blood loss, and length of hospital stay. Results: Data from 192 patients were available. The ODI at 2 years correlated weakly to moderately with age (r = 0.4), BMI (r = 0.2), ASA (r = 0.3), and LIV (r = 0.2), and strongly with preoperative ODI (r = 0.6). The leg VAS at 2 years moderately correlated with age (r = 0.3) and BMI (r = 0.3). Conclusion: ODI and VAS at 2 years’ follow-up had no to little association to preoperative age, health status, LIV, or other peroperative data, but showed a strong correlation with preoperative ODI and pain level.

P24. Acute failure of S2-alar-iliac pelvic fixation following adult deformity correction

BACKGROUND CONTEXT Pelvic fixation with S2-alar-iliac (S2AI) screws is a widely accepted technique in adult deformity surgery, with few descriptions of complications. PURPOSE To report novel acute failure mechanisms in S2AI instrumentation. STUDY DESIGN/SETTING Retrospective chart review. PATIENT SAMPLE N/A OUTCOME MEASURES N/A METHODS We performed a retrospective review of all fusion surgeries extending from L2 or higher with instrumentation to the pelvis in which S2AI screws were placed with at least 6 months follow-up between 3/2017 and 6/2019. We excluded patients under 18 years of age and non-ambulatory patients. Acute instrumentation failure was defined as any case requiring revision of the pelvic fixation within 6 months from the index surgery. We reviewed the demographic and surgical characteristics of each patient, and reviewed preoperative and 6-week postoperative radiographs to document the change in their deformity parameters as well as for the presence of a transitional lumbo-sacral segment. RESULTS A total of 134 cases were identified, of which seven had acute S2AI instrumentation failure requiring revision (5%). Failure cases averaged age 56.6 years, BMI 32.5, 57% female, 12 levels of fusion, and average deformity correction was LL increase 32°, T1PA decrease 19°, and CSVL decrease 3.5cm. Failure mechanism was either set plug dislodgement from S2AI screw heads, sacral fracture/kyphosis with rod slippage out of S2AI set plugs, or both, and involved two different implant manufacturers. Three of seven (43%) failure patients had a nonmobile transitional segment at the lumbosacral junction and fractured through the transitional segment with kyphotic angulation. Salvage strategy involved removal and revision of the original S2AI screws with placement of additional stacked pelvic fixation and a multi-rod construct. CONCLUSIONS We have identified a novel mechanism of pelvic fixation failure involving set screw dislodgement and rod slippage, which affected 5% of the deformity patients in our series across two implant manufacturers. Patients with large angular deformity correction and/or transitional lumbosacral anatomy may be particularly at risk, and may benefit from supplemental pelvic fixation. FDA DEVICE/DRUG STATUS S2AI Screws (Approved for this indication), thoracolumbosacral pedicle screw system (Approved for this indication).

P92. Does BMI over 40 have a significant risk in spine deformity patients?

BACKGROUND CONTEXT Morbid obesity, and specifically body mass index (BMI) over 40 is a known risk factor for postoperative complications. There is scarcity of literature, however, studying whether BMI>40 is an independent risk factor for complication in surgical spine deformity patients. PURPOSE To evaluate whether morbid obesity is a risk factor in spine deformity patients. STUDY DESIGN/SETTING Retrospective case study. PATIENT SAMPLE Patients who underwent spinal deformity surgery from national database. OUTCOME MEASURES Specific complications (DVT, pneumonia, etc.), ICU level complications (cardiac arrest, stroke, PE, etc). METHODS Patients undergoing surgery for adult deformity correction were identified in the American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP) database from 2006 to 2016. Inclusion criteria were CPT codes for deformity surgery, a combination of ICD 9 and 10 codes for deformity (kyphosis, scoliosis, proximal junctional kyphosis, etc.) along with a combination of CPT codes for a 5 or more level fusion. Two groups were established as follows: those with BMI =40. RESULTS A total of 2,869 patients fit the inclusion criteria. Average age was 56.4 and 63.6% were female. BMI over or equal to 40 was a predictor of overall complications (p=0.032) and ICU level complications (p=0.003) on univariate analysis. Interestingly, the rate of wound infections, DVT and pneumonias did not differ significantly between the groups, although these complications are often thought to be associated with high BMI. The rate of renal complications (p=0.036), cardiac arrest (p=0.008) and reintubations (p=0.004) was significantly higher in the BMI>=40 group. On multivariate analysis BMI over 40 remained a significant predictor of ICU level complications, even when controlled for dependent functional status, diabetes, and hypertension (statistically significant differences between the groups). CONCLUSIONS BMI greater than 40 is an independent predictor of ICU level complications in patients undergoing surgery for spinal deformity. Contradictory to common belief, however, it does not seem to infer greater risk of wound infections, DVTs, or pneumonias in this patient subgroup. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.

Anterolateral and Posterior versus Posterior-Only Approaches for the Correction of Degenerative Adult Spinal Deformity

Anterolateral and Posterior versus Posterior-Only Approaches for the Correction of Degenerative Adult Spinal Deformity

Independent Association Between Type of Intraoperative Blood Transfusion and Postoperative Delirium After Complex Spinal Fusion for Adult Deformity Correction.

Retrospective cohort study. To determine whether type of intraoperative blood transfusion used is associated with increased incidence of postoperative delirium after complex spine fusion involving five levels or greater. Postoperative delirium after spine surgery has been associated with age, cognitive status, and several comorbidities. Intraoperative allogenic blood transfusions have previously been linked to greater complication risks and length of hospital stay. However, whether type of intraoperative blood transfusion used increases the risk for postoperative delirium after complex spinal fusion remains relatively unknown. The medical records of 130 adult (≥18 years old) spine deformity patients undergoing elective, primary complex spinal fusion (more than or equal to five levels) for deformity correction at a major academic institution from 2010 to 2015 were reviewed. We identified 104 patients who encountered an intraoperative blood transfusion. Of the 104, 15 (11.5%) had Allogenic-only, 23 (17.7%) had Autologous-only, and 66 (50.8%) had Combined transfusions. The primary outcome investigated was the rate of postoperative delirium. There were significant differences in estimated blood loss (Combined: 2155.5 ± 1900.7 mL vs. Autologous: 1396.5 ± 790.0 mL vs. Allogenic: 1071.3 ± 577.8 mL vs. None: 506.9 ± 427.3 mL, P < 0.0001) and amount transfused (Combined: 1739.7 ± 1127.6 mL vs. Autologous: 465.7 ± 289.7 mL vs. Allogenic: 986.9 ± 512.9 mL, P < 0.0001). The Allogenic cohort had a significantly higher proportion of patients experiencing delirium (Combined: 7.6% vs. Autologous: 17.4% vs. Allogenic: 46.7% vs. None: 11.5%, P = 0.002). In multivariate nominal-logistic regression analysis, Allogenic (odds ratio [OR]: 24.81, 95% confidence interval [CI] [3.930, 156.702], P = 0.0002) and Autologous (OR: 6.43, 95% CI [1.156, 35.772], P = 0.0335) transfusions were independently associated with postoperative delirium. Our study suggests that there may be an independent association between intraoperative autologous and allogenic blood transfusions and postoperative delirium after complex spinal fusion. Further studies are necessary to identify the physiological effect of blood transfusions to better overall patient care and reduce healthcare expenditures. 3.

208. Predictors of superior recovery kinetics in adult cervical deformity correction: an analysis using a novel area under the curve methodology

BACKGROUND CONTEXT Novel analyses of clinical outcomes following cervical deformity (CD) corrective surgery use an area-under-the-curve (AUC) method to assess health-related quality of life (HRQL) metrics throughout the surgical recovery process. It remains unclear how demographics, preop parameters, and surgical decisions are associated with superior recovery. PURPOSE Identify demographic, surgical and radiographic factors that predict superior recovery kinetics. STUDY DESIGN/SETTING Retrospective review of a prospective CD database. PATIENT SAMPLE A total of 98 CD patients. OUTCOME MEASURES Baseline (BL) to 1-year (1Y) HRQL Instruments: Neck Disability Index (NDI). METHODS CD database criteria:C2-7 Cobb angle>10°, coronal Cobb angle >10°, cSVA>4cm or TS-CL>10°, or CBVA>25°. Following univariate analyses, the AUC normalization method was utilized by dividing all reported BL and postoperative(3M, 1Y) outcome measures by the BL score. Normalized scores(y-axis) were plotted against follow-up time interval(x-axis). Total area was calculated for all follow-up, divided by cumulative follow-up length, determining overall, time-adjusted HRQL recovery (Integrated Health State[IHS]). IHS NDI scores were stratified by quartile, the uppermost 25% were categorized as having “superior” recovery kinetics (SRK) vs “normal” recovery kinetics (NRK). BL demographic, clinical and surgical information were used to predict SRK using generalized linear modeling. RESULTS A total of 98 patients included(62±10yrs, 28±6kg/m2, 65%F). Mean CCI: 0.95, 6% smokers, and 31% history of smoking. Surgical approach: combined(33%), posterior(49%), anterior(18%). Average posterior levels fused: 8.7, anterior levels fused: 3.6, EBL: 915.9ccs, op time: 495min. According to the Ames CD classification at BL: cSVA (53.2% minor deformity and 46.8% moderate), TS-CL (9.8% minor, 4.3% moderate, 85.9% marked), and horizontal gaze (27.4% minor, 46.6% moderate, 26% marked). Relative to BL NDI scores (mean: 47), normalized postop NDI scores showed decrease in disability at 3M(0.9±0.5, p=0.260) and a further decrease at 1Y (0.78±0.41, p CONCLUSIONS Superior recovery kinetics following cervical deformity surgery was predicted with high accuracy using a combination of baseline patient reported factors(VAS EQ5D, swallow sleep, and mJOA scores) and radiographic factors(TK, T10-T12, T12-S1, L1-S1). Patients and health care providers should be aware of these factors in order to improve surgical decision-making, in an effort to reduce postop neck disability. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.

Reduced Influence of Affective Disorders on 6-Week and 3-Month Narcotic Refills After Primary Complex Spinal Fusions for Adult Deformity Correction: A Single-Institutional Study

Previous studies have identified the impact of affective disorders on preoperative and postoperative perception of pain. However, there is a scarcity of data identifying the impact of affective disorders on postdischarge narcotic refills. The aim of this study was to determine whether patients with affective disorders have more narcotic refills after complex spinal fusion for deformity correction. The medical records of 121 adult (≥18 years old) spine deformity patients undergoing elective, primary complex spinal fusion (≥5 level) for deformity correction at a major academic institution from 2010 to 2015 were reviewed. Patient demographics, comorbidities, intraoperative and postoperative complication rates, baseline and postoperative patient-reported pain scores, ambulatory status, and narcotic refills were collected for each patient. The primary outcome was the rate of 6-week and 3-month narcotic refills. Of the 121 patients, 43 (35.5%) had a clinical diagnosis of anxiety or depression (affective disorder) (ADn= 43; No-AD n= 78). Preoperative narcotic use was significantly higher in the AD cohort (AD 65.9% vs. No-AD 37.7%, P= 0.0035). The AD cohort had significantly higher pain scores at baseline (AD 6.5 ± 2.9 vs. No-AD 4.7 ± 3.1, P=0.004) and at the first postoperative pain score reported (AD 6.7 ± 2.6 vs. No-AD 5.6 ± 2.9, P= 0.049). However, there were no significant differences in narcotic refills at 6 weeks (AD 34.9% vs. No-AD 25.6%, P= 0.283) and 3 months (AD23.8% vs. No-AD 17.4%, P= 0.411) after discharge between the cohorts. Our study suggests that whereas spinal deformity patients with affective disorders may have a higher baseline perception of pain and narcotic use, the impact of affective disorders on narcotic refills at 6 weeks and 3 months may be minimal after complex spinal fusion.

Association Between Age and Short-Term Patient Reported Pain Scores After Complex Spinal Fusion for Adult Deformity Correction: Is Perception of Pain Different?

Association Between Age and Short-Term Patient Reported Pain Scores After Complex Spinal Fusion for Adult Deformity Correction: Is Perception of Pain Different?

Association Between Preoperative Narcotic Use with Perioperative Complication Rates, Patient Reported Pain Scores, and Ambulatory Status After Complex Spinal Fusion (≥5 Levels) for Adult Deformity Correction

The widespread over-use of narcotics has been increasing. However, whether narcotic use impacts surgical outcomes after complex spinal fusion remains understudied. The aim of this study was to evaluate whether there is an association between preoperative narcotic use with perioperative complication rates, patient-reported pain scores, and ambulatory status after complex spinal fusions. The medical records of 134 adult (age ≥18 years) patients with spinal deformity undergoing elective, primary complex spinal fusion (≥5 levels) for deformity correction in a major academic institution from 2005-2015 were reviewed. Patient demographics, comorbidities, intraoperative and postoperative complication rates, pain scores, and ambulatory status were collected for each patient. Patient demographics and comorbidities were similar between both cohorts, except that the Narcotic-User cohort had a greater mean age (57.5 years vs. 50.7 years; P= 0.045) and prevalence of depression (39.4% vs. 16.2%; P= 0.003). Complication rates were similar between both cohorts. The Narcotic-User cohort had significantly higher pain scores at baseline (6.7 ± 2.4 vs. 4.0 ± 3.4; P < 0.001) and at the first postoperative pain score reported (6.7 ± 2.8 vs. 5.3 ± 2.9; P= 0.013), but had a significantly greater improvement from baseline to last pain score (Narcotic-User: -2.5 ± 3.9 vs. Non-User: -0.5 ± 4.7; P= 0.031). The Narcotic-User cohort had significantly greater ambulation on the first postoperative ambulatory day compared with the Non-User cohort (103.8 ± 144.4 vs. 56.4 ± 84.0; P= 0.031). Our study suggests that the preoperative use of narcotics may impact patient perception of pain and improvement after complex spinal fusions (≥5 levels). Consideration of patients' narcotic status preoperatively may facilitate tailored pain management and physical therapy regimens.

Reduced Impact of Obesity on Short-Term Surgical Outcomes, Patient-Reported Pain Scores, and 30-Day Readmission Rates After Complex Spinal Fusion (≥7 Levels) for Adult Deformity Correction

In the past decade, prevalence of obesity in the United States have been soaring at a disparaging rate. Previous spine studies have associated obesity with inferior surgical outcomes, increased complication and 30-day readmission rates, and worsening patient-reported outcomes. However, there is a paucity of data identifying whether the impact of obesity is sustained in patients undergoing complex deformity correction involving 7 levels or greater. The aim of this study was to determine whether obesity impacts surgical outcomes, patient-reported pain scores, and 30-day readmission rates after complex spinal fusions ≥7 levels. The medical records of 112 adult patients (≥18 years old) with spine deformity undergoing elective, primary complex spinal fusion (≥7 levels) for deformity correction at a major academic institution from 2010 to 2015 were reviewed. Preoperative body mass index greater than or equal to 30 kg/m2 was classified as obese. Patient demographics, comorbidities, and intraoperative and postoperative complication rates were collected for each patient. Inpatient patient-reported pain scores and ambulatory status also were collected. The primary outcomes of this study were surgical outcomes, patient-reported pain scores, and 30-day readmission rates. Of the 112 patients, 33 (29.5%) were obese (obese: n = 33 vs. non-obese: n = 79). Patient demographics and comorbidities were similar between both cohorts, including age, sex, diabetes, hypertension, and home narcotic use. The median number of fusion levels operated, length of surgery, estimated blood loss, transfusion, and complication rates were similar between both cohorts. Moreover, the postoperative complication profiles between the cohorts also were similar, with a comparable length of hospital stay (obese: 6.5 ± 4.6 days vs. non-obese: 7.0 ± 3.9 days, P = 0.5833) and 30-day readmission rates (obese: 12.1% vs. non-obese: 13.9%, P = 0.7984). Baseline (P = 0.6826), first (P = 0.9691), and last (P = 0.9583) postoperative patient-reported pain scores were similar between cohorts. Analogously, ambulatory status was similar between the cohorts, including days from operating room to ambulation (P = 0.3471) and number of steps on first (P = 0.9173) and last (P = 0.1634) ambulatory day before discharge. Our study suggests that obesity does not significantly affect surgical outcomes, patient-reported pain scores, and 30-day readmission rates after complex spinal surgery requiring ≥7 levels of fusion. Further studies are necessary to corroborate our findings.

Rate of instrumentation changes on postoperative and follow-up radiographs after primary complex spinal fusion (five or more levels) for adult deformity correction.

OBJECTIVEIn the United States, healthcare expenditures have been soaring at a concerning rate. There has been an excessive use of postoperative radiographs after spine surgery and this has been a target for hospitals to reduce unnecessary costs. However, there are only limited data identifying the rate of instrumentation changes on radiographs after complex spine surgery involving ≥ 5-level fusions.METHODSThe medical records of 136 adult (≥ 18 years old) patients with spine deformity undergoing elective, primary complex spinal fusion (≥ 5 levels) for deformity correction at a major academic institution between 2010 and 2015 were reviewed. Patient demographics, comorbidities, and intra- and postoperative complication rates were collected for each patient. The authors reviewed the first 5 subsequent postoperative and follow-up radiographs, and determined whether revision of surgery was performed within 5 years postoperatively. The primary outcome investigated in this study was the rate of hardware changes on follow-up radiographs.RESULTSThe majority of patients were female, with a mean age of 53.8 ± 20.0 years and a body mass index of 27.3 ± 6.2 kg/m2 (parametric data are expressed as the mean ± SD). The median number of fusion levels was 9 (interquartile range 7-13), with a mean length of surgery of 327.8 ± 124.7 minutes and an estimated blood loss of 1312.1 ± 1269.2 ml. The mean length of hospital stay was 6.6 ± 3.9 days, with a 30-day readmission rate of 14.0%. Postoperative and follow-up change in stability on radiographs (days from operation) included: image 1 (4.6 ± 9.3 days) 0.0%; image 2 (51.7 ± 49.9 days) 3.0%; image 3 (142.1 ± 179.8 days) 5.6%; image 4 (277.3 ± 272.5 days) 11.3%; and image 5 (463.1 ± 525.9 days) 15.7%. The 3rd year after surgery had the highest rate of hardware revision (5.55%), followed by the 2nd year (4.68%), and the 1st year (4.54%).CONCLUSIONSThis study suggests that the rate of instrumentation changes on radiographs increases over time, with no changes occurring at the first postoperative image. In an era of cost-conscious healthcare, fewer orders for early radiographs after complex spinal fusions (≥ 5 levels) may not impact patient care and can reduce the overall use of healthcare resources.

Intraoperative ketamine may increase risk of post-operative delirium after complex spinal fusion for adult deformity correction.

For complex surgery, intraoperative ketamine administration is readily used to reduce post-operative pain. However, there have been a few studies suggesting that intraoperative ketamine may have deleterious effects and impact post-operative delirium. Therefore, we sought to identify the impact that intraoperative ketamine has on post-operative outcomes after complex spinal surgery involving ≥5 level fusions. The medical records of 138 adult (≥18 years old) spine deformity patients undergoing elective, primary complex spinal fusion (≥5 level) for deformity correction at a major academic institution from 2010 to 2015 were reviewed. We identified 98 (71.0%) who had intraoperative ketamine administration and 40 (29%) who did not (Ketamine-Use: n=98; No-Ketamine: n=40). Patient demographics, comorbidities, intra- and post-operative complication rates were collected for each patient. The primary outcome investigated in this study was the rate of post-operative delirium. A multivariate nominal-logistic regression analysis was used to determine the independent association between intraoperative ketamine and post-operative delirium. Patient demographics and comorbidities were similar between both cohorts, including age, gender, and BMI. The median number of fusion levels operated, length of surgery, estimated blood loss, and proportion of patients requiring blood transfusions were similar between both cohorts. Postoperative complication profile was similar between the cohorts, except for the Ketamine-Use cohort having significantly higher proportion of patients experiencing delirium (Ketamine-Use: 14.3% vs. No-Ketamine: 2.6%, P=0.047). In a multivariate nominal-logistic regression analysis, intraoperative Ketamine-Use was independently associated with post-operative delirium (OR: 9.475, 95% CI: 1.026-87.508, P=0.047). Our study suggests that the intraoperative use of ketamine may increase the risk of post-operative delirium. Further studies are necessary to understand the physiological effect intraoperative ketamine has on patients undergoing complex spinal fusions in order to better overall patient care and reduce healthcare resources.

161 Association Between Preoperative Narcotic Use With Surgical Outcomes, Patient Reported Pain Scores and Ambulatory Status After Complex Spinal Fusion (≥5 Levels) for Adult Deformity Correction

161 Association Between Preoperative Narcotic Use With Surgical Outcomes, Patient Reported Pain Scores and Ambulatory Status After Complex Spinal Fusion (≥5 Levels) for Adult Deformity Correction

Saturday, September 29, 2018 9:00 am–10:00 am Impact of Adult Deformity Correction: 262. The effect of surgical alignment on gait complexity in adult deformity patients: a neuromuscular synergy approach

BACKGROUND CONTEXT Adult degenerative scoliosis (ADS) patients frequently suffer from impairments in mobility. Surgical intervention for ADS mostly improves gait, balance and other health-related quality of life scores. Previous literature demonstrates that the central nervous system (CNS) might use an organization of muscle synergies to control a wide range of activities, for example walking. Instead of controlling each muscle individually, the CNS groups the muscles and activates many them with a single control signal. Hence, neuromuscular synergies may indicate the ability of the CNS in generating independent control signals. Less number of muscle synergies during walking emphasizes inability of the CNS to generate as many independent control signals. The higher number of synergies represents the higher gait complexity since more number of control inputs are required to achieve the same task. PURPOSE To compare number of walking muscle synergies in ADS patients both before and 3 months postsurgery. STUDY DESIGN/SETTING A prospective concurrent control cohort study. PATIENT SAMPLE A total of 13 ADS patients. OUTCOME MEASURES Gait complexity by number of muscle synergies. METHODS Clinical gait analysis was performed one week prior and 3 months postsurgery. Five walking trials were performed at comfort speed. Surface electromyography (EMG) electrodes were placed and recorded bilaterally from 16 trunk and lower extremity muscles: external oblique, gluteus maximus, multifidus, erector spinae, rectus femoris, semitendinosus, tibialis anterior, medial gastrocnemius. EMG data was collected at 2,000 Hz, filtered, rectified, and normalized. The processed EMG was mathematically broken into synergies and their activation ratio (from 100%). The higher number of synergies always reduces the residual error between the reconstructed EMG and the original EMG. The required number of synergies were defined as the minimum number of synergies that could reconstruct EMG signals with subtracting 5% error ([EMGoriginal -EMGreconstructed] = e, e/EMGoriginal RESULTS Clinical gait analysis was performed one week prior and 3 months postsurgery. Five walking trials were performed at comfort speed. Surface electromyography (EMG) electrodes were placed and recorded bilaterally from 16 trunk and lower extremity muscles: external oblique, gluteus maximus, multifidus, erector spinae, rectus femoris, semitendinosus, tibialis anterior and medial gastrocnemius. EMG data was collected at 2,000 Hz, filtered, rectified and normalized. The processed EMG was mathematically broken into synergies and their activation ratio (from 100%). The higher number of synergies always reduces the residual error between the reconstructed EMG and the original EMG. The required number of synergies were defined as the minimum number of synergies that could reconstruct EMG signals with subtracting 5% error {(EMGoriginal -EMGreconstructed) = e, e/EMGoriginal CONCLUSIONS This study shows an increase in gait complexity by increase in number of synergies following a surgical alignment in ADS patients. More number of synergies postsurgery shows a more elaborate gait pattern since more number of synergies (modules) are required to rebuild the EMG signals, in addition to improvements in ability of the CNS in generating more number of independent or rich control signals. As an example, inability of poststroke patients in generating independent control signals for gait makes their CNS to activate numerous muscles with a single signal (at the same time), causing unwanted co-contractions that hinders their normal gait. We recommend that spine care providers use gait analysis as part of their clinical evaluation to provide an objective measure of function and to better understand the effects of the disease and its treatment on their patients’ gait, function, and, ultimately, quality of life. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.

Saturday, September 29, 2018 9:00 am–10:00 am Impact of Adult Deformity Correction: 263. Development of deployable predictive models for MCID of 2-year outcomes across all commonly used HRQOL instruments in adult spinal deformity surgery: results in 570 patients from 17 hospitals

BACKGROUND CONTEXT Adult spinal deformity (ASD) surgery is costly with variable outcomes; in some series only 50% of patients achieve clinically important (MCID) improvements. Predictive modeling with machine learning is a relatively unexplored area of patient-reported outcomes research. These methods may be useful in shared-decision making, surgical planning, and postoperative patient counseling. PURPOSE To use predictive analytics to model health-related quality of life (HRQOL) outcomes at 1 year and 2 years after ASD surgery; including predicting the likelihood of achieving MCID. STUDY DESIGN/SETTING Data from two unique, multicenter, prospective observational cohort studies PATIENT SAMPLE Patients 18 years or older and treated for ASD with surgery. OUTCOME MEASURES Scoliosis Research Society-22, Oswestry Disability Index, Short Form-36v2. METHODS Two multi-center, prospective observational cohorts of ASD patients were queried to identify patients with complete enrollment, 1 and 2-year follow-up SRS-22, ODI and SF-36v2 data. Standard demographic and radiographic variables were collected. Modifiable surgical data (eg, 3-Column Osteotomy Yes or No), intraoperative and postoperative complications were collected. A total of 75 variables were used in the training of the models. Eight different prediction algorithms were trained with 3-time horizons: baseline to 1 year, baseline to 2 years, and 1 year to 2 years. External validation was accomplished via an 80/20 data split for training and testing each model, respectively. Five-fold cross validation within the training sample was performed. Accuracy was measured as the mean average error (MAE; smaller is better) and R² values. Models were created to predict HRQOL values at 2 years and to predict the likelihood of achieving MCID thresholds at 2 years postoperatively. RESULTS A total of 570 patients were included in the analysis. Models with the lowest MAE for each of the 5-time points were selected, achieving 82.4% predictive power. Patients with lower enrollment HRQOL were likely to achieve the greatest improvements and enrollment HRQOL values were the most important variables included. Age at enrollment was the most important demographic variable. Addition of surgeon and site to preoperative data increased the predictive power 1.8%. Site and surgeon fixed-effects played a crucial role in explaining outcome variance. Levels fused and enrollment curve magnitude were less important. CONCLUSIONS Predictive modeling from a large cohort of ASD patients was able to model 2-year outcomes scores, including the likelihood of achieving clinically relevant improvements. Patients with the lowest HRQOL scores were likely to appreciate the greatest improvements at 2 years postoperatively. Surgeon and site were important covariates, explaining variance in outcomes measures. These data may be used in informed decision making and patient counseling before and after ASD surgery. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.